I. Field of the Invention
The present invention relates to a magnetic bubble memory device and, more particularly, to a magnetic bubble memory device having a control circuit suitable for controlling magnetic bubble memory chips having different storage capacities.
II. Description of the Prior Art
In general, a magnetic bubble memory is of a shift register type, and magnetic bubbles propagate bit by bit in synchronism with a rotating magnetic field whose flux rotates within the plane of the magnetic bubble memory chip. The bubble memory chip generally has a major-minor loop system and has various functions such as a function for generating a magnetic bubble, a replicator function for replicating the magnetic bubble, a transfer-in gate function for transferring the magnetic bubble from a major loop to a minor loop, a transfer-out gate function for transferring the magnetic bubble from the minor loop to the major loop, and a detector function for detecting the magnetic bubble. Since the magnetic bubble memory chip having the above functions is operated to propagate the magnetic bubble in synchronism with the rotating magnetic field, operating parameters for these functions are required.
FIG. 1 is an enlarged plan view showing the main part of a conventional major-minor loop type magnetic bubble memory chip having write and read lines. Referring to FIG. 1, reference numeral 1 denotes a set of minor loops for a magnetic bubble memory; 2, a write line of the magnetic bubble; and 3, a read line thereof. A generator 4 generates a magnetic bubble on the write line 2. A transfer-in gate 5 transfers the magnetic bubble written on the write line 2 to the minor loop 1. A replicator/transfer-out gate 6 transfers the magnetic bubble on a minor loop 1 to the read line 3, and divides the magnetic bubble and returns a divided part to the minor loop 1. A detector 7 detects the magnetic bubble.
The following parameters are required to operate the magnetic bubble memory chip having the construction described above: a bit number parameter m indicating the number of bits in each minor loop 1; a minor loop number parameter; a bit number parameter n.sub.1 indicating the number of bits ranging from the generator 4 to the transfer-in gate 5; a bit number parameter n.sub.2 indicating the number of bits ranging from the replicator/transferout gate 6 to the detector 7; and a bit number parameter n.sub.3 indicating the number of bits ranging from the replicator/transfer-out gate 6 to the transfer-in gate 5.
In the conventional magnetic bubble memory device of the type described above, these parameter data are set in a control circuit (not shown). These data are used to control generation of pulse signals required for the various functions, and hence to control the magnetic bubble memory chip.
However, these parameters are given at the time of magnetic bubble memory chip design. For this reason, conventional magnetic bubble memory chips having different storage capacities cannot be controlled by a single control circuit. In order to control a magnetic bubble memory chip having a different storage capacity, a separate parameter setting circuit is required. Demands have arisen for interchangeably using bubble memory chips having different capacities in a single memory. The conventional magnetic bubble memory devices, however, cannot satisfy these demands.